The practice of using heat energy for aesthetic treatment and body shaping is known in the art. Heating of the skin and the underlying tissues over certain temperatures or temperature ranges results in tissue shrinkage and produces a desired aesthetic effect. The application of RF energy is one of the methods of heating the skin and underlying tissues.
Aesthetic and/or body shaping treatment is administered using an applicator coupled with an RF electrode or energy delivery device connected to a source of RF. The electrode typically has an RF energy delivery surface. The surface is applied to the surface of the skin and couples to it the RF energy, which produces heat transferred into the skin and underlying subcutaneous tissues to create the desired effect that may be tissue shrinkage, wrinkle removal, collagen distraction, acne removal, etc. The heat induced in the skin and underlying subcutaneous tissues by the RF energy is not distributed in a balanced way across the electrode surface coupled with the skin, especially in the places where the skin does not form a good contact across the whole surface of the electrode. Segments of skin being in contact with the electrode surface receive a higher dose of RF energy and form so called “hot spots”. In many situations, the temperature of the hot spots is high enough to damage the skin. In order to avoid the skin overheating, and in some cases skin burns, the whole electrode is cooled by a cooling fluid or other type of coolant. The author of the present method has theoretically and experimentally established that in addition to hot spots a larger amount of energy concentrates along the periphery of the electrode energy delivery surface and more specifically at the corners and edges of the electrode. In order to improve heat distribution over the skin surface that is coupled with the electrode, electrodes with rounded edges and corners were produced and tested. The rounded edges and corners have, to some extent, mitigated the heating effect, but the skin segments that are adjacent to the electrodes are still excessively heated by the RF.
Because of this uneven RF energy distribution across the electrode, achieving an effective treatment RF energy level across the electrode and in particular at the center portion of the electrode energy delivery surface, results in excessive heating at the energy delivery surface periphery and corners. This causes undesired pain and possible damage to the skin and underlying subcutaneous tissue coupled with these peripheral areas and corners. This phenomenon precludes achieving a sufficiently high, but safe level of energy that can be coupled to the skin through the RF electrode.